1. Field of the Invention
The present invention relates to an ink jet printing apparatus configured to perform printing by ejecting ink to a print medium and a method for filling ink into an ink tank mounted in the ink jet printing apparatus.
2. Description of the Related Art
According to Japanese Patent Laid-Open No. 2001-113716, to eliminate the possible need to replace an ink tank during an operation of printing a print medium, a structure of an ink jet printing apparatus that uses a subtank separately from a main tank is described. In the ink jet printing apparatus disclosed in the specification, ink is supplied from the main tank, which is replaceable and has a large capacity, to the subtank, which has a relatively small capacity. The ink stored in the subtank is supplied to the print head.
Hence, even if the ink in the main tank is exhausted during printing of one print medium, a certain amount of ink still remains in the subtank. The ink stored in the subtank can be used to continue printing. Then, the printing operation can be achieved without interruption by completing replacement of the main tank while printing is being performed with ink supplied from the subtank. As a result, the quality of print images can be kept high.
In the printing apparatus disclosed in Japanese Patent Laid-Open No. 2001-113716, the print head and the subtank are mounted in a carriage. The main tank is located separately from the carriage, with an ink channel extending from the main tank to the subtank. The ink channel extending from the main tank to the subtank is allowed to contact and leave the subtank. A pump is located in the ink channel extending from the main tank, to supply ink from the main tank to the subtank.
However, the pump configured to supply ink from the main tank to the subtank is often expensive. In general, the pump requires arrangements such as a driving source, a transmission mechanism configured to transmit a driving force generated by the driving source, and the ink channel, and so on. Thus, the pump requires relatively high costs compared to the other components forming the printing apparatus. Moreover, the printing apparatus configured to supply ink from the main tank to the subtank requires an exhaust air mechanism. The exhaust air mechanism requires, for example, a valve configured to allow the subtank to communicate with the atmosphere and to break the communication between the subtank and the atmosphere and a driving mechanism for the valve, or the pump. The exhaust air mechanism may thus have a complicated and expensive configuration.